Flower care

Planting Density The number of plants to grow per square metre, or the planting density, is a trade-off between increased yield and decreased quality. While close spacing produces increased yields per square metre it results in smaller flowers and lower quality. Stems are generally weaker and longer due to the decreased light levels. The incidence of disease can be higher due to the decrease in air movement caused by the crowding. Increased space between plants results in better quality, but lower yields per square metre. Planting density varies with plant size, the number of years between replanting, the sensitivity of the crop to disease, the method of harvest and the staking requirements. It also varies with each plant species; most seed catalogues or supplier’s guides give recommended spacings. Some spacing principles are common to most crops. For example, the larger the size of the mature plant the more room that will be needed between plants. Gypsophila will need much more room than a smaller plant like zinnia. In general, perennials are planted less dense than annuals to allow for the several years of growth between digging up and splitting. Plants that are prone to foliar diseases, for example snapdragons, which are susceptible to powdery and downy mildew, will benefit from a wider spacing due to the increased air circulation. Perennials which need staking may benefit from an increased density where the flower stems tend to support each other